Boston cellular networks flooded, but service was not cut off

In light of this afternoon's tragedy at the Boston Marathon, many across the world scrambled to contact loved ones through calls, texts, and social media. Cellular providers had beefed up their networks in advance of the Marathon, but even with the extra capacity the networks became flooded, leading to reports of users being unable to make calls.

There was confusion this afternoon when the Associated Press reported that cell service in the city would be intentionally shut off as police looked to prevent any possible cellular activation of another explosive. However, the news organization basically retracted its original story and found no such shutdown was ordered. The carriers said heavy usage caused connection delays—but service remained available in the city throughout the day.

"Verizon Wireless has not been asked by any government agency to turn down its wireless service. Any reports to that effect are inaccurate," Verizon spokesman Tom Pica told the IDG News Service in an e-mail.

The AP's initial report came from an anonymous law enforcement official, citing an intelligence briefing that supposedly outlined the service shutdown. The FCC later told ABC News it was not aware of any cellular shutdowns, and the news outlet confirmed the same with Sprint, AT&T, and Verizon. (T-Mobile had a similar message for VentureBeat.)

Connection difficulties occurred despite each carrier taking precautions before the race to boost service. Sprint spokeswoman Crystal N. Davis told ABC News that the carrier did "augment capacity on its cell sites along the marathon route" to prepare for the roughly 27,000 runners (plus friends, family, and fans) passing through. T-Mobile also upped its capacity. And after the incident unfolded, these carriers took actions to strengthen their offerings. The message to text instead of call spread throughout the city, Verizon enhanced its network voice capacity in the Copley Square area, and AT&T turned on extra Wi-Fi capacity "for an extended timeframe."

Ultimately, service wasn't suspended though it certainly experienced connectivity issues. In light of the congestion, companies like Google sought to help people locate others through services like Person Finder.

Promoted Comments

Shutting it off would have been a good idea. A good reason though to have other communication systems for emergencies at the ready.

Edit: On second consideration, if it became common practice to shut off cell service during such events then I would guess other methods (radio, old fashioned timers) would become the norm. In that case the loss to public communication would be too much a trade off.

As far as emergency communications are concerned, Boston refuses to do away with its system of emergency call boxes on city streets. People keep demanding they dump it, or swap the boxes out for cellular-based replacements, but the fire department refuses to budge on the issue.

Why?

It doesn't break. Ever. While individual boxes go down occasionally, the network does not. The system was installed in 1851 and has continued to function without a single mass-outage in over 150 years. That kind up uptime is insane. Think about it. The thing has been running nonstop since before the US Civil War.

On 9/11/01, you simply couldn't call in any kind of emergency in NYC. Later, in 2004, the 911 system crashed for hours and NYC's remaining call boxes were again the only way to get help.

Call boxes are telegraph-based, which means they don't rely on any other city infrastructure. The deaf and blind can use them with ease. You don't need to speak English. You don't need to know where you are. You just need to pull a cover and then a hook. That's it. Straightforward and tactile.

Boston is very explicit that it doesn't care what kind of emergency you use it for. It doesn't need to be a fire. Car accident? Pull it. Someone following you? Pull it.

It's provided as both a convenience and the absolute last-ditch way to save your life or the life of someone else that will never, ever fail to summon help.

I was listening to the live feed of the Boston Fire Department radio scanner, and they announced ahead of time over their network that they were going to shut down the cellular networks, and then announced as it was going down. This was right after they found the JFK Library explosive. As a veteran of Saudi Arabia, Iraq, and Afghanistan, this was a good idea. It wasn't to shut down communications, it was to shut down cell phone activated explosives.

It's easy enough to imagine a dispatcher broadcasting those messages in error after being passed an inaccurate notice that the network would come down at a certain time.

Remember that taking the network down would also come at a cost, with the potential for loss of life as well. Doctors need to communicate with other doctors or with staff about medical conditions of patients. Patients may have trouble contacting their doctors about situations they don't realize are serious enough to call 911 about. Local poison control numbers might become unavailable to those in need. Non emergency issues could flood emergency numbers making 911 unavailable. People might do stupid things when they can't contact loved ones. And so on.

You also need to consider that decision makers need a fair amount of information before they can take action which has other dangers, and time is needed to gather that information. As time goes by, the value of shutting down the network goes down while the disadvantages remain the same or climb.

Such a decision is not as straightforward as many think, which could be why a decision to take the network down may have been over-ridden after the message that a take-down was imminent was distributed.

65 Reader Comments

Shutting it off would have been a good idea. A good reason though to have other communication systems for emergencies at the ready.

Edit: On second consideration, if it became common practice to shut off cell service during such events then I would guess other methods (radio, old fashioned timers) would become the norm. In that case the loss to public communication would be too much a trade off.

Shutting it off would have been a good idea. A good reason though to have other communication systems for emergencies at the ready.

No shutting it off would be a bad idea as there is no guaranty that whoever built the bombs didn't design them with a heartbeat system to auto detonate were it to lose signal.

Given that such a design is probably less likely (I've heard of cellular detonated bombs set off by terrorists in the Middle East, but never with a "heartbeat" system), it seems the odds are in fact better that killing the network would prevent other bombs from going off.

Like the above poster mentions, your method just has a much worse chance of working. Even if it does have a heartbeat, you're still leaving the manual detonation option open.

EDIT: For my 2 cents, I'd say the value of allowing open communication like that outweighs the possibility of other bombs detonating, especially since multiple bombs like this seems to be the exception rather than the rule.

Shutting it off would have been a good idea. A good reason though to have other communication systems for emergencies at the ready.

This time they shut it down "for the terrorists", next time they'll shut it down "to stop those pesky dissidents". They already bend over and help the government violate the Fourth Amendment; I'd hate to see them start helping to violate the First Amendment too.

Shutting it off would have been a good idea. A good reason though to have other communication systems for emergencies at the ready.

This time they shut it down "for the terrorists", next time they'll shut it down "to stop those pesky dissidents". They already bend over and help the government violate the Fourth Amendment; I'd hate to see them start helping to violate the First Amendment too.

I was listening to the live feed of the Boston Fire Department radio scanner, and they announced ahead of time over their network that they were going to shut down the cellular networks, and then announced as it was going down. This was right after they found the JFK Library explosive. As a veteran of Saudi Arabia, Iraq, and Afghanistan, this was a good idea. It wasn't to shut down communications, it was to shut down cell phone activated explosives.

I was listening to the live feed of the Boston Fire Department radio scanner, and they announced ahead of time over their network that they were going to shut down the cellular networks, and then announced as it was going down. This was right after they found the JFK Library explosive. As a veteran of Saudi Arabia, Iraq, and Afghanistan, this was a good idea. It wasn't to shut down communications, it was to shut down cell phone activated explosives.

It's easy enough to imagine a dispatcher broadcasting those messages in error after being passed an inaccurate notice that the network would come down at a certain time.

Remember that taking the network down would also come at a cost, with the potential for loss of life as well. Doctors need to communicate with other doctors or with staff about medical conditions of patients. Patients may have trouble contacting their doctors about situations they don't realize are serious enough to call 911 about. Local poison control numbers might become unavailable to those in need. Non emergency issues could flood emergency numbers making 911 unavailable. People might do stupid things when they can't contact loved ones. And so on.

You also need to consider that decision makers need a fair amount of information before they can take action which has other dangers, and time is needed to gather that information. As time goes by, the value of shutting down the network goes down while the disadvantages remain the same or climb.

Such a decision is not as straightforward as many think, which could be why a decision to take the network down may have been over-ridden after the message that a take-down was imminent was distributed.

Shutting it off would have been a good idea. A good reason though to have other communication systems for emergencies at the ready.

This time they shut it down "for the terrorists", next time they'll shut it down "to stop those pesky dissidents". They already bend over and help the government violate the Fourth Amendment; I'd hate to see them start helping to violate the First Amendment too.

1) Have you not read the article at all? It was not deliberately shut down.

2) Not everything is part of a grand conspiracy to oppress people.

3) By "for the terrorists" are you trying to trivialize what just happened to all those people on Boston?

Really? No one has anything to say about this??? AT&T just decided to flip on the "more Wi-Fi" switch ... awesome ... can we keep that friggin' flipped on all the time?!

My impression is that this was some sort of band-aid measure that wasn't designed for long-term use, so they could handle the occasional large gathering of people in one area. Perhaps they pushed some of the equipment harder than is strictly advisable, or diverted capacity that would normally have been used to carry voice calls or SMS messages.This is similar to how nuclear power plants use gas turbines to handle short spikes in power demand. You don't want to use the turbines except for short bursts, because they're much less efficient.

Really? No one has anything to say about this??? AT&T just decided to flip on the "more Wi-Fi" switch ... awesome ... can we keep that friggin' flipped on all the time?!

My impression is that this was some sort of band-aid measure that wasn't designed for long-term use, so they could handle the occasional large gathering of people in one area. Perhaps they pushed some of the equipment harder than is strictly advisable, or diverted capacity that would normally have been used to carry voice calls or SMS messages.This is similar to how nuclear power plants use gas turbines to handle short spikes in power demand. You don't want to use the turbines except for short bursts, because they're much less efficient.

Good grief folks, you don't get out much....

This is bog standard for large events - they've done it for years. They typically bring in mobile cell towers and assorted equipment, hook up any spare capacity they have and work with the other networks to make a temporarily larger capacity network. They don't leave them there for a number of reasons, cost being the biggest, the temporary towers likely another big issue. Remember, there are only a limited number of places that you can put a permanent tower and they're expensive so the CellCo has to balance out availability and costs (insert your favorite AT&T joke here). Not everyone wants a cell tower in their planter and not every planter has the backhaul and power capacity to support a cell phone antenna.

They don't 'push' equipment - you can't turn the dial to 11. The nuclear power plant isn't a good example - they don't like to be throttled much. What the power company does is to have fast start 'peaking plants', typically natural gas fueled turbines that can spin up quickly when demand peaks.

Really? No one has anything to say about this??? AT&T just decided to flip on the "more Wi-Fi" switch ... awesome ... can we keep that friggin' flipped on all the time?! wtf

No, there isn't a "more Wi-Fi" switch at an AT&T central office somewhere. As a wild guess I would say that AT&T had already deployed more equipment into public spaces for the marathon and will now keep that deployed for an extended time. Perhaps they also managed to get more equipment into the area which was destined for another.

Still, I do enjoy the mental image of a huge lever at a central office labeled "Wi-Fi" being controlled by the Charlie Chaplin character from Modern Times.

Shutting it off would have been a good idea. A good reason though to have other communication systems for emergencies at the ready.

This time they shut it down "for the terrorists", next time they'll shut it down "to stop those pesky dissidents". They already bend over and help the government violate the Fourth Amendment; I'd hate to see them start helping to violate the First Amendment too.

<snip>3) By "for the terrorists" are you trying to trivialize what just happened to all those people on Boston?

I daresay ATimson was demonstrating the slippery-slope down which a suggestion that shutting off (cell) phone service for a perceived good can slide. I don't see his comment trivializing what happened in Boston at all. Rather, the comment reminds me of First they came....

Shutting down (cell) phone service to prevent an act of terrorism (or the furthering of one) is an action with which most would agree - especially in the moment. Doing so once, though, makes it easier to do a second time, and then an third; each time (cell) phone service is temporarily restricted for "public safety", the barrier to doing so tends to get weakened, until shutting it down to quiet "those pesky dissidents" seems a logical step when protesters march on Washington (or a state capitol building, or...).

I was listening to the live feed of the Boston Fire Department radio scanner, and they announced ahead of time over their network that they were going to shut down the cellular networks, and then announced as it was going down. This was right after they found the JFK Library explosive. As a veteran of Saudi Arabia, Iraq, and Afghanistan, this was a good idea. It wasn't to shut down communications, it was to shut down cell phone activated explosives.

It's easy enough to imagine a dispatcher broadcasting those messages in error after being passed an inaccurate notice that the network would come down at a certain time.

Remember that taking the network down would also come at a cost, with the potential for loss of life as well. Doctors need to communicate with other doctors or with staff about medical conditions of patients. Patients may have trouble contacting their doctors about situations they don't realize are serious enough to call 911 about. Local poison control numbers might become unavailable to those in need. Non emergency issues could flood emergency numbers making 911 unavailable. People might do stupid things when they can't contact loved ones. And so on.

You also need to consider that decision makers need a fair amount of information before they can take action which has other dangers, and time is needed to gather that information. As time goes by, the value of shutting down the network goes down while the disadvantages remain the same or climb.

Such a decision is not as straightforward as many think, which could be why a decision to take the network down may have been over-ridden after the message that a take-down was imminent was distributed.

My concern with shutting down the cellular network is that you disrupt many heavily used communication channels that you might need to have open.

Also, depending on the sophistication of the bomber(s) one could have triggered a timer by the cellphone. Say each bomb has a delay of 1 hour, the phone call would have been earlier and shutting off the network would do absolutely nothing. I would not be surprised if a diligent search of the Internet would turn up information about making such as device.

Shutting it off would have been a good idea. A good reason though to have other communication systems for emergencies at the ready.

Edit: On second consideration, if it became common practice to shut off cell service during such events then I would guess other methods (radio, old fashioned timers) would become the norm. In that case the loss to public communication would be too much a trade off.

As far as emergency communications are concerned, Boston refuses to do away with its system of emergency call boxes on city streets. People keep demanding they dump it, or swap the boxes out for cellular-based replacements, but the fire department refuses to budge on the issue.

Why?

It doesn't break. Ever. While individual boxes go down occasionally, the network does not. The system was installed in 1851 and has continued to function without a single mass-outage in over 150 years. That kind up uptime is insane. Think about it. The thing has been running nonstop since before the US Civil War.

On 9/11/01, you simply couldn't call in any kind of emergency in NYC. Later, in 2004, the 911 system crashed for hours and NYC's remaining call boxes were again the only way to get help.

Call boxes are telegraph-based, which means they don't rely on any other city infrastructure. The deaf and blind can use them with ease. You don't need to speak English. You don't need to know where you are. You just need to pull a cover and then a hook. That's it. Straightforward and tactile.

Boston is very explicit that it doesn't care what kind of emergency you use it for. It doesn't need to be a fire. Car accident? Pull it. Someone following you? Pull it.

It's provided as both a convenience and the absolute last-ditch way to save your life or the life of someone else that will never, ever fail to summon help.

Shutting it off would have been a good idea. A good reason though to have other communication systems for emergencies at the ready.

Edit: On second consideration, if it became common practice to shut off cell service during such events then I would guess other methods (radio, old fashioned timers) would become the norm. In that case the loss to public communication would be too much a trade off.

As far as emergency communications are concerned, Boston refuses to do away with its system of emergency call boxes on city streets. People keep demanding they dump it, or swap the boxes out for cellular-based replacements, but the fire department refuses to budge on the issue.

Why?

It doesn't break. Ever. While individual boxes go down occasionally, the network does not. The system was installed in 1851 and has continued to function without a single mass-outage in over 150 years. That kind up uptime is insane. Think about it. The thing has been running nonstop since before the US Civil War.

On 9/11/01, you simply couldn't call in any kind of emergency in NYC. Later, in 2004, the 911 system crashed for hours and NYC's remaining call boxes were again the only way to get help.

Call boxes are telegraph-based, which means they don't rely on any other city infrastructure. The deaf and blind can use them with ease. You don't need to speak English. You don't need to know where you are. You just need to pull a cover and then a hook. That's it. Straightforward and tactile.

Boston is very explicit that it doesn't care what kind of emergency you use it for. It doesn't need to be a fire. Car accident? Pull it. Someone following you? Pull it.

It's provided as both a convenience and the absolute last-ditch way to save your life or the life of someone else that will never, ever fail to summon help.

Keep in mind, there's only so many operators there to answer emergency calls, so if they're all tied up answering other calls, it doesn't really matter what communications system you have. Even if pulling the lever in a call box lights up an LED on some dispatch operator's monitor or whatever, that's not going to help in a situation like 9/11, where there's simply no-one left to come and help you.

1. Please consider donating blood.2. Yes you can levar (burton) more cellular juice , you tell the towers to update the handsets less.often by reducing data rate. You can do it on the phones using input codes also and it would be common practice during large public events because cellular codecs are loss and jitter tolerant. this isn't recent either. they can also revert your connection to lower standards by forcing it to legacy 2g and such gear which whilst normally not in use is left on the cell towers when new things like Lte come along. 3. See point 1 please I would but I'm.in Australia :<

At NZNOG 2012 (Network Operators Group) there was a fantastic talk by the Alcatel-Lucent guy working on the Telecom NZ's XT network and how they altered it after the Christchurch 2011 earthquakes. This is an interesting video on how cellular providers actually deal with major disasters and the impact it has on their network: http://www.r2.co.nz/20120126/jed-l.htm

Shutting it off would have been a good idea. A good reason though to have other communication systems for emergencies at the ready.

This time they shut it down "for the terrorists", next time they'll shut it down "to stop those pesky dissidents". They already bend over and help the government violate the Fourth Amendment; I'd hate to see them start helping to violate the First Amendment too.

1) Have you not read the article at all? It was not deliberately shut down.

2) Not everything is part of a grand conspiracy to oppress people.

3) By "for the terrorists" are you trying to trivialize what just happened to all those people on Boston?

He's not saying they shut it down this time, he's saying the justification for shutting it down, if they did. And it's very legitimate. Already anyone that opposed the government's actions over the last decade and a half was labeled as anti-american, and Dubya himself said outright that you're either on his side or against him.

Further, you're ignoring his very legitimate point that it's not a hypothetical, it IS a slippery slope with a DOCUMENTED instance of exactly the kind of abuse he mentions.

Another poster is also correct in that in OUR society and country, the damage caused by cutting off those communications could and likely would potentially cause far more damage, whereas the odds of another explosive that simply hadn't gone off yet is relatively low, as typically you set delayed explosions to herd, for example, a convoy into position to hit them harder; by the time they could get the message out to shut down the network, and actually effect that shutdown, all the explosives are likely to have already been detonated.

Contrast that previous paragraph with the locations we normally see cell-phone activated bombs: largely rural areas with little dependence on that infrastructure. Lower population densities and less medical help available in the first place. The damage done by a shutdown would likely be less than the benefit of preventing a detonation.

Before someone mentions it, jamming signals are also a terrible idea, as this is as likely to set off a bomb as prevent its detonation. There is very specific guidance with regard to controlling RF emissions within various distances from a UXO or IED.

I'm speaking here as someone with first-hand experience, as well as family in the Boston area (fortunately it only took me about 2 hours to get hold of them and know they're ok). I'm active duty US Air Force. The odds are higher that shutting down the networks would cause more harm than help, and the larger issue of future abuse is anything but trivial, never mind a conspiracy theory (after all, we have a documented example in the US of it being used to stifle protests, and countless examples of the same across the world.)

"In shutting down cell service, you block the ability to create that circuit and ignite that fuse. In the military we would use jamming devices on our trucks, sometimes seven or eight of them on a single vehicle."

So, basically, the excuse that you are denied the capability to call 911 cannot be used to punish service providers, especially in the case where BART shut down cell service to prevent protest coordination. Accessing 911 services is not a right that can be infringed. That's the gist of the logic I gather from this, unfortunately.

Shutting it off would have been a good idea. A good reason though to have other communication systems for emergencies at the ready.

This time they shut it down "for the terrorists", next time they'll shut it down "to stop those pesky dissidents". They already bend over and help the government violate the Fourth Amendment; I'd hate to see them start helping to violate the First Amendment too.

At least in this case it would have been a clear instance of protecting public safety.

They don't need cell phones to trigger a bomb remotely. Walkie talkies can be effective over 10 miles. Every countermeasure causes terrorists to evolve, and the measures we take leave people in a precarious situation because we mistakenly believe it will make us safer.

As far as emergency communications are concerned, Boston refuses to do away with its system of emergency call boxes on city streets. People keep demanding they dump it, or swap the boxes out for cellular-based replacements, but the fire department refuses to budge on the issue.

Why?

It doesn't break. Ever. While individual boxes go down occasionally, the network does not. The system was installed in 1851 and has continued to function without a single mass-outage in over 150 years. That kind up uptime is insane. Think about it. The thing has been running nonstop since before the US Civil War.

On 9/11/01, you simply couldn't call in any kind of emergency in NYC. Later, in 2004, the 911 system crashed for hours and NYC's remaining call boxes were again the only way to get help.

Call boxes are telegraph-based, which means they don't rely on any other city infrastructure. The deaf and blind can use them with ease. You don't need to speak English. You don't need to know where you are. You just need to pull a cover and then a hook. That's it. Straightforward and tactile.

Boston is very explicit that it doesn't care what kind of emergency you use it for. It doesn't need to be a fire. Car accident? Pull it. Someone following you? Pull it.

It's provided as both a convenience and the absolute last-ditch way to save your life or the life of someone else that will never, ever fail to summon help.

Damn, that's one hell of a system. Good on Boston for having the sense to keep it in place

"In shutting down cell service, you block the ability to create that circuit and ignite that fuse. In the military we would use jamming devices on our trucks, sometimes seven or eight of them on a single vehicle."

This seems ill-advised. It wouldn't actually be any more difficult to design the bomb to go off on loss of connection, or on detection of a strong jamming signal indicating a vehicle nearby. You've basically got the vehicles broadcasting a "target is here" signal.

Also, what military was this? There seems to be a lot of scams in the bomb detection business, with one prominent case where governments (including Iraq, Thailand, and others) and police were being sold what were basically empty boxes with an antenna for $40,000 each. It'd hopefully be more obvious if a jammer doesn't work, but it's enough to make me suspicious of such things.

"In shutting down cell service, you block the ability to create that circuit and ignite that fuse. In the military we would use jamming devices on our trucks, sometimes seven or eight of them on a single vehicle."

This seems ill-advised. It wouldn't actually be any more difficult to design the bomb to go off on loss of connection, or on detection of a strong jamming signal indicating a vehicle nearby. You've basically got the vehicles broadcasting a "target is here" signal.

Also, what military was this? There seems to be a lot of scams in the bomb detection business, with one prominent case where governments (including Iraq, Thailand, and others) and police were being sold what were basically empty boxes with an antenna for $40,000 each. It'd hopefully be more obvious if a jammer doesn't work, but it's enough to make me suspicious of such things.

Sure as hell wasn't the US military. As I said, specific guidance on RF emissions near potential explosive devices, and "transmit a signal strong enough to block out all others" (i.e., EXACTLY what a jammer does) is definitely not in the "do this" category.

"In shutting down cell service, you block the ability to create that circuit and ignite that fuse. In the military we would use jamming devices on our trucks, sometimes seven or eight of them on a single vehicle."

This seems ill-advised. It wouldn't actually be any more difficult to design the bomb to go off on loss of connection, or on detection of a strong jamming signal indicating a vehicle nearby. You've basically got the vehicles broadcasting a "target is here" signal.

I'm still trying to find it, but I'm sure I read an article on the evolution of IEDs in Iraq and Afghanistan that confirmed your statement. The bombers started by sending a signal to trigger detonation. Coalition forces began jamming the signals to prevent detonation, so the bombers re-configured and rigged the IEDs to explode if they lost a signal due to jamming. We adapt, they adapt in response.

"In shutting down cell service, you block the ability to create that circuit and ignite that fuse. In the military we would use jamming devices on our trucks, sometimes seven or eight of them on a single vehicle."

This seems ill-advised. It wouldn't actually be any more difficult to design the bomb to go off on loss of connection, or on detection of a strong jamming signal indicating a vehicle nearby. You've basically got the vehicles broadcasting a "target is here" signal.

I'm still trying to find it, but I'm sure I read an article on the evolution of IEDs in Iraq and Afghanistan that confirmed your statement. The bombers started by sending a signal to trigger detonation. Coalition forces began jamming the signals to prevent detonation, so the bombers re-configured and rigged the IEDs to explode if they lost a signal due to jamming. We adapt, they adapt in response.

It's hardly a new concept; it's not like the idea is from Terminator 2, it's been around as long as electronically-activated systems have been around (and likely predates even that, as a dead-man's switch could be mechanical in nature as well, e.g. holding down a lever that, when released, causes, say, a break to engage.)

"In shutting down cell service, you block the ability to create that circuit and ignite that fuse. In the military we would use jamming devices on our trucks, sometimes seven or eight of them on a single vehicle."

This seems ill-advised. It wouldn't actually be any more difficult to design the bomb to go off on loss of connection, or on detection of a strong jamming signal indicating a vehicle nearby.

I think it would be significantly harder to design a signal loss trigger. The obvious way to trigger with a cell phone is tap into the vibrator motor...a modest amount of readily accessible and remotely controllable current. Any hack can do it. Using loss of signal introduces plenty of additional complexities.

Yeah, a phone has no direct I/O way of reporting signal via pins you can tap into. I guess if you wanted to integrate bluetooth into your bomb you may be able to get signal strength that way, but even that is unrelable.

"In shutting down cell service, you block the ability to create that circuit and ignite that fuse. In the military we would use jamming devices on our trucks, sometimes seven or eight of them on a single vehicle."

This seems ill-advised. It wouldn't actually be any more difficult to design the bomb to go off on loss of connection, or on detection of a strong jamming signal indicating a vehicle nearby.

I think it would be significantly harder to design a signal loss trigger. The obvious way to trigger with a cell phone is tap into the vibrator motor...a modest amount of readily accessible and remotely controllable current. Any hack can do it. Using loss of signal introduces plenty of additional complexities.

While potentially trickier with a cell phone signal as opposed to some other method, it would take all of a week's worth of learning to program to make an application respond to the initial message in the desired way. Also, as had already been pointed out, even if not a dead man's switch the remote trigger can just as easily activate a timer as it could trigger detonation directly. The modern smartphone opens up worlds of possibility here. Just look at the ability to set your DVR via a website; there's absolutely NOTHING preventing the exact same thing being implemented here, provided sufficient motivation. Is it as likely? Probably not, but it's absolutely plausible.

I think it would be significantly harder to design a signal loss trigger. The obvious way to trigger with a cell phone is tap into the vibrator motor...a modest amount of readily accessible and remotely controllable current. Any hack can do it. Using loss of signal introduces plenty of additional complexities.

It's not. I can think of a couple ways to do it right off-hand that don't require anything but very basic web programming and simple electronics, possibly without even installing a custom app. If you use the vibrator or speaker signal to periodically reset a timer, you don't even need that much.

And in the case of vehicles with jammers, you don't have to use loss of signal, as you've got a powerful transmitter conveniently already placed on the target for you...just a moderately well-tuned RF detector will do the job.

"In shutting down cell service, you block the ability to create that circuit and ignite that fuse. In the military we would use jamming devices on our trucks, sometimes seven or eight of them on a single vehicle."

This seems ill-advised. It wouldn't actually be any more difficult to design the bomb to go off on loss of connection, or on detection of a strong jamming signal indicating a vehicle nearby. You've basically got the vehicles broadcasting a "target is here" signal.

Also, what military was this? There seems to be a lot of scams in the bomb detection business, with one prominent case where governments (including Iraq, Thailand, and others) and police were being sold what were basically empty boxes with an antenna for $40,000 each. It'd hopefully be more obvious if a jammer doesn't work, but it's enough to make me suspicious of such things.

The original concept was not to jam a device to keep it from going off, it was, hopefully, to trigger the device before the vehicle reached a device, or in the case of vehicle born devices intended to be parked and later detonated to detonate a device after an area was cleared of personnel. It was our military, and every nations military that has been in the area in the last 13 years not only those but contractors for just about everything from food services to security, plus there have been cases where the terrorist their selves have used them when they were not sure if some IED's were in the area or not.

The vast majority of cell phone detonators are the call-n-detonate variety - phone rings, vibrates, etc... the IED explodes. That's because most IED's are intended to be triggered when a specific target is in a kill zone, and that takes someone watching and when they see the target in the kill zone they make the call.

The bombs at the Boston Marathon, there was a third device removed from the same general area as the two that went off. The ones that did go off were low yield explosives, indicated by videos from the scene (generally the lower the yield the more smoke produced from the explosion, especially with home made explosives, possibly a home made grade explosive but time and investigation will tell. The low angle of explosion force, indicated by videos from the scene, indicated a primary soft target personnel focus and the use of shrapnel in the devices later confirmed. The bombs followed the somewhat standard pattern, first goes off then 15 - 20 seconds later the next goes of, so forth and so on till all are detonated. The reason for this is to cause the first primary injuries/kills then to detonate later bombs to get any responders to the first explosion, in an effort to increase the number of injuries/kills especially among the responders for later bombs to delay help getting to the scene so those wounded which may have been saved will in theory die from their injuries such as blood loss. The reason they were set where they were and across from other buildings was to get the greatest concentration of people and responders and to 'amplify' the concussive and shrapnel force (ricochet of shrapnel). Cell phone detonators weren't immediately indicated but the investigation jury is still out, there was one carrier that supposedly went dark for a up to a few minutes as a result of the carriers own internal emergency procedures in such an event if a cell phone detonator is suspected when the third unexploded device was discovered, but overall cell phone service did not go down and instead was simply overloaded. If there was a cell phone detonator, Its possible the third device could not go off because the bombers could not get through because the service was overloaded (or maybe because that one carrier went down for a short period).